Plural stage refrigeration apparatus



May 11, 1954 w U 2,677,944

PLURAL STAGE REFRIGERATION APPARATUS Filed Dec. 1, 1950 3 Sheets-Sheet lI l l I L EI APOZAZ'ORS 25 V 25 J2 INVENTOR 4/0020 Ruff ATTORNEY May 11,1954 w, RUFF 2,677,944

PLURAL STAGE REFRIGERATION APPARATUS 3 Sheets-Sheet 2 Filed Dec. 1, 1950II II.' I

INVENTOR 6/ V I /4/ 0/720 M fluff ATTORNEY y 11, 1954 A. w. RUFF2,677,944

PLURAL STAGE REFRIGERATION APPARATUS 3 Sheets-Sheet 3 2%. 5.

Filed Dec. 1, 1950 INVENTOR 4/0/720 W Ruff ATTORNEY Patented May 11,1954 PLURAL STAGE REFRIGERATION APPARATUS Alonzo W. Ruff, York, Pa.Application December 1, 1950, Serial No. 198,602

Claims.

This invention relates to refrigeration systems and more particularly toa booster compressor stage, and improvements in the cooling and sealingof booster compressors.

In mechanical refrigeration systems of the compressor-condenser-expandercircuit type, it is ofte desirable to increase the refrigerationcapacity of the system. Increased capacity may be necessary in order topermit the handling of deep frozen food products now in wide use, ortopermit research laboratory tests at relatively low temperatures. Theimproved compressor disclosed herein has been found well suited foraddition to existing refrigeration systems to greatly increaserefrigeration capacity by making it possible to lower the effectiveevaporator temperature.

It is an object of this invention to provide an efiicient boostercompressor for initially compressing a gaseous refrigerant medium.

It is another object of this invention to provide a refrigerantcompressor having improved cooling and sealing means.

It is another object of this invention to provide a refrigerantcompressor which is relatively small in size and easily installed inexisting refrigeration systems.

It is a still further object of this invention to provide a boostercompressor, together with cooling and sealing circuits, which iseflicient in operation and relatively low in cost.

Other objects, advantages and features of the present invention willbecome readily apparent from the following description of the embodimentillustrated in the accompanying drawings where- 1n:

Figure 1 is a diagrammatic illustration of a refrigeration systemincluding a booster comprescor stage.

Figure 2 is a horizontal sectional view of a preferred form ofcompressor and taken on line 22 of Figure 3.

Figure 3 is a vertical sectional view taken on line 3-4 of Figure 2.

Figure 4 is a diagrammatic illustration of a preferred arrangement ofcooling and sealing circuits for the compressor shown in Figures 1, 2and. 3.

Figure 5 is a diagrammatic illustration of a modified arrangement ofcooling and sealing circuits.

Referring to the drawings, the exemplary embodiment of the invention isshown applied to a closed refrigeration system including evaporators I land I 2 supplied with liquified gaseous refrigerant from a receiver I3by line It. The gaseous refrigerant from the evaporators H and I2 isconducted to compressors l5 and It by line I! and passes to thecondensers I8 through line l9, and liquified refrigerant from thecondensers is collected in the receiver 13. Conventional details such asevaporator, compressor and receiver controls, and condenser coolingmeans are not shown in the diagrammatic illustration. The compressorbooster stage includes a compressor connected in the line I! between theevapo rators and the conventional compressors I5 and It. A duplicatecompressor may be connected in parallel with the compressor 20 whererequired. An intercooler 2! may also be connected in the gas line I!between the booster 2i! and the compressors l5 and I5. Suitable valvesare provided in connection with line I? for connecting-in or by-passingthe booster 20 and the intercooler 2|. The booster compressor 20 isprovided with a cooling jacket described hereinafter, and the liquidcooling medium utilized in said jacket may be passed through a heatdissipating coil 22 located, for example, in the floor of a room orchamber containing the evaporators H and I2 to prevent freezing andbuckling of such floors.

Referring to Figures 2 and 3, the booster compressor 20 is preferably ofthe rotary vane type having a casing 25 with a cylindrical bore. Thecasing 25 is provided with an inlet 26 and with an outlet 2'! forgaseous refrigerant. The casing 25 is provided with a head 28 at one endhaving an oif-center bearing 29 for the cylindrical rotor 30. The head28 is closed by a plate 3|. The other end of the casing 25 is providedwith a head 32 also containing an off-center bearing 33 for the driveshaft 3% extending outward from the rotor 30. Sliding vanes 35, radiallydisposed, are arranged in slots in the rotor and are urged outward intocontact with the inner surface of the casing 25 when the rotor is drivenby the shaft 34. A shaft seal casing 36 is secured to the head 32 andincludes spaced packing members 31 and 3B engaging the drive shaft 34. Aflap-type check valve 39 may be provided in the compressor outlet 2.1,and a lubricant inlet 40 may be provided in the inlet 26. The compressorshaft 34 may be driven by any suitable means such as the direct drivemotor 4! illustrated in Figure 4. The motor li may be in line with thecompressor shaft 34 and be coupled thereto by a suitable coupling 52, orthe motor may be mounted above the compressor 20 to conserve space, inwhich event a belt and pulley, chain, or gear drive may be used.

The compressor casing Figure 5, is provided with passages 45 forming acooling jacket surrounding the rotor 35. An inlet and an outlet d5 areconnected to the cooling jacket passages 45. The head 23 is alsoprovided with passages 38 communicating with the passages d5 to permitcooling of the shaft bearing 29. The head 32 has similar passages 49communicating with the passages 45 for cooling the bearing 33. The shaftseal casing 36 is provided with passages 56 connected with the coolantoutlet 45 by the line 55 and with the coolant inlet by line 5? forcooling the shaft seals 8? and 38. Casing 36 also has an inlet 51 and anoutlet 52, Figure 2, for the chamber 53 between the seals 3": and 38 sothat liquid under sufficient pressure may be provided in said chamber toprevent any leakage of air into the compressor and to prevent anyleakage of refrigerant gas outward through the seal 31.

The cooling and sealing circuits illustrated in Figure 4 will now bedescribed. The compressor 28 is cooled by an anti-freeze liquid, such asoil, circulated through the jacket passages 45, 48, 4S, and 56, by meansof pump 65. Hot liquid from the compressor jackets may, for example, becirculated through the lines 54 and 62 to a coil 22 embedded in thefloor of a low temperature refrigerated space to prevent floor buckling,or it may be circulated through the cooler 6|, the latter being aconventional heat exchanger including coils through which cold water maybe circulated. The cooled liquid is then pumped into the jacket inletfill and into line 5! to the seal jacket 5%. Cooling liquid may be addedto this circuit at an expansion tank 63. The circulated cooling liquidcools the compressor bearings 29 and 33 as well as the shaft seals 31and 38.

Liquid, such as oil, is supplied to the shaft seal chamber 53 throughinlet 5!! and may be circu lated by pump ti; connected to the outlet 52,as shown in Figure 4. The sealing oil is pumped by pump 68 through astrainer 6'! and thence through line 68 to a seal oil pct 89. The closedoil pct 69 may be provided with a cooling coil 18 through which water iscirculated and may have a filler cap ii to permit the addition of oil tothe sealing oil circuit. Sealing oil flows from the pct 69 through lines22 and 13 back to the seal housing inlet 5!. The sealing oil may bepassed through a coil is wrapped around the compressor gas inlet pipe"i5, if desired, for cooling the seal oil. The compressed gas outlet 21is provided with a cut off valve St in the line 8|. A pipe 82 conductscompressor outlet pressure through a two-way check valve unit 83 to theseal oil line E2. The check valve unit 83 comprises two check valves 8dand 85. The check valves may be spring loaded ball type check valves, asshown in Figure 5, and valve 84 is effective to communicate thecompressor outlet pressure in line Si or in compressor outlet 21 to thesealing liquid in line 72. Valve 85 is effective to vent excessivepressures in the sealing liquid line ll! to the compressor outlet line.The check valve unit 8 5 may be connected directly to the compressoroutlet line 2'! as shown by the line 86 in Figure 5. This alternativeconnection 86 is also shown in dotted lines in Figure 4. Other forms ofpressure equalizing devices, such as diaphragms, bellows, pistons, orthe like, may be used in place of the double check valve unit 83.

The modified seal oil system shown in Figure 5 is similar to that shownin Figure 4 except that the seal oil is not circulated by a pump and2.5, as shown best in not cooled other than by the cooling jacketpassages 50 in the seal casing 36. In the Figure 5 system the passage 50is provided with an inlet 5| but has not outlet connection. The inlet 5|is connected to an oil pot 88 which may have a visual sight gauge 89 toindicate the level of seal oil in the oil pot 88. The top of the oil pct68 is provided with a filler cap 90 and is connected by line 12 to thedouble check valve unit 83 described hereinbefore. The unit 83 may beconnected to the compressor outlet 21 by line 86 for the pur pose ofmaintaining compressor outlet pressure on the seal oil in chamber 53.

The operation of the systems disclosed will now be described. Lowpressure gaseous refrigerant from the evaporators II and I2 iscompressed in compressors [5 or 16, cooled in condenser i8, and theliquid refrigerant collected in receiver l3 from which it is circulatedback to the evaporators II or [2. In order to boost the refrigerationcapacity of this closed system, the rotary vane type compressor 20 isconnected in the gaseous refrigerant line between the evaporator l2 andthe compressor l5. The booster compressor 20, in a typical installation,may compress the gaseous refrigerant, such as ammonia gas, to pressuresof the order of thirty-five pounds per square inch and the high stagecompressors l5 and It increase this intermediate pressure to a pressureof the order of one hundred and eighty-five pounds per square inch. Thecompressed gaseous refrigerant from the booster compressor 20 may becooled by the intercooler 2| before it reaches the high stagecompressors l5 and IS. The rotary vane compressor 20 is cooled by thecirculation of a suitable anti-freeze liquid, such as oil, through thejacket passages 45, 48, 49, and 50, by means of pump 60. The heat in thecooling liquid flowing from the compressor jackets may be dissipated inthe coil 22 located in the floor of the evaporator chamber orrefrigerated space; or, it may b dissipated in the cooler 6|. Thecooling liquid from outlet 46 then passes back to the jacket inlet 41 bylines 62 and 64, an expansion tank 63 being connected in the line. Inthe Figure 5 modification, the cooling liquid from outlet 45 passesthrough line 56 to the sealing cooling jacket 50 and then through line51 to the cooler 6 l pump 68, and inlet 41. The double seal 31-38 on thedrive shaft 34 of the booster compressor 20 is cooled by the coolingliquid in the passage 59. A sealing liquid such as oil is supplied tothe space 53 between the seals 31 and 38 and is maintained at a pressureabout equal to the compressor outlet pressure to prevent air fromleaking into the compressor during operation and to prevent refrigerantgas from leaking out through the seal 31 during stand-by. The sealingliquid pressure is maintained by the equalizing check valve unit 83, andwhere the sealing liquid is externally cooled it is circulated by pump66 for cooling in the oil pct 69 or by the coil 14 on the compressorinlet line 15. Both the cooling liquid circuit and the sealing liquidcircuit are closed circuits, and these circuits are independent of eachother. The pressure in the sealing liquid circuit is automaticallycontrolled by the pressure existing in the compressor outlet, and may beheld at a limited positive pressure during compressor operation as wellas during standby. The maintenance of positive pressure on the sealingliquid during standby is particularly important when two or more rotarycompressors 20 are operated in parallel and one is shut down, because avacuum condition could exist throughout a compressor and air might leakthrough the sealinto the refrigerant in the compressor except as the oilpressure seal is maintained. The circulation of coolingjacket liquidthrough coils in the floor of a low temperature storag room, thusprotecting the earth under the floor from freezing and buckling thefloor, is an advantageous economy since the need for cooling water isavoided and the need for a separate source of heat to warm floor pipingis also avoided.

The present invention contemplates the use of various forms of rotarycompressors, pumps, heat exchangers, valves, automatic controls, etc, asit will be readily apparent to the skilled refrigeration engineer thatmany such variations are possible within the scope of the followingclaims.

I claim:

1. A system for cooling and sealing a rotary type refrigerant gascompressor in which a liquid coolant is circulated in a closed circuitwhich includes a jacket surrounding the compressor and a jacket whichsurrounds the sealing means for the driven end of the compressor shaft,comprising: pump means for circulating the liquid coolant in both ofsaid jackets; housing means for containing a liquid sealing medium inconfined contact with the driven end of the compressor shaft; andpressure communicating means connected with the compressor outlet formaintaining pressure equal to compressor outlet pressure on th saidsealing medium.

2. A system for cooling and sealing a rotary type refrigerant gascompressor in which a liquid coolant is circulated in a closed circuitwhich includes a jacket surrounding the compressor and a jacket whichsurrounds the sealing means for the driven end of the compressor shaft,comprising: means for circulating the coolant in both of said jackets,said means including a circulating pump and a heat exchanger fordissipating heat from said coolant; housing means for containing aliquid sealing medium in confined contact with the driven end of thecompressor shaft; and pressure communicating means connected with thecompressor outlet for maintaining compressor outlet pressure on the saidsealing medium.

3. A system for cooling and sealing a rotary type refrigerant gascompressor in which a coolant is circulated in a closed circuit whichincludes a jacket a jacket which surrounds the sealing means for thedriven end of the compressor shaft, comprising: means for circulatingthe coolant in both of said jackets, said means including a circulatingpump and a heat dissipating coil associated with the floor of arefrigerated chamber; housing means for containing a liquid sealingmedium in confined contact with the driven end of the compressor shaft;and means connected with the compressor outlet for maintainingcompressor outlet pressure on the said sealing medium.

4. A system for cooling and sealing a rotary type refrigerant gascompressor in which a liquid coolant is circulated in a closed circuitwhich includes a jacket surrounding the compressor and a jacket whichsurrounds the sealing means for the driven end of the compressor shaft,comprisingz means for circulating the coolant through both of saidjackets; a closed sealing medium circuit for circulating a liquidsealing medium into contact with the driven end of the compressor shaft,said circuit including a circulating pump, a heat exchanger, and apressure communicating connection with the compressor outlet formaintaining a pressure on the sealing surrounding the compressor and rlit medium in contact with said compressor shaft as high as the normaloutlet pressure of said compressor.

5. A system for cooling and sealing a rotary type refrigerant gascompressor in which a liquid coolant is circulated in a closed circuitwhich ineludes a jacket surrounding the compressor and a jacket whichsurrounds the sealing means for the driven end of the compressor shaft,comprising: a closed coolant circuit including a circulating pump and aheat exchanger connected for circulating the coolant in both of saidjackets; a closed sealing medium circuit including a circulating pumpand a heat exchanger connected for circulating a sealing liquid inconfined contact with the driven end of said compressor shaft; and apressure communicating connection between said sealing medium circuitand the outlet of said compressor for maintaining a pressure on thesealing medium in contact with said shaft at least as high as thecompressor outlet pressure.

6. A cooling and sealing system as recited in claim 5 in which saidpressure communicating connection includes a check valve.

7. A cooling and sealing system as recited in claim 5 in which saidconnection includes two valves maintaining compressor outlet pressure onsaid sealing medium, the other of said valves relieving excess pressureon said sealing valve into said compressor outlet.

8. A booster compressor stage for a closed refrigeration system, saidstage comprising a refrigerant gas compressor in which a liquid coolantis circulated in a closed circuit which includes a jacket surroundingthe compressor and a jacket which surrounds sealing means for the drivenend of the compressor shaft, means for circulating the coolant in bothof said jackets, housing means for containing a liquid sealing medium inconfined contact with the driven end of the compressor shaft, and meansconnected with the compressor outlet for maintaining pressure on saidsealing medium.

9. A booster compressor stage for a closed refrigeration system, saidstage comprising a rotary refrigerant gas compressor in which a liquidcoolant is circulated in a closed circuit which includes a. jacketsurrounding the compressor and a jacket which surrounds sealing meansfor the driven end of the compressor shaft, said circuit including acirculating pump and a heat exchanger for dissipating heat from saidcoolant, housing means for containing a liquid sealing medium inconfined contact with the driven end of said compressor shaft, andpressure communicating means including a check valve connected with thecompressor outlet for maintaining a pressure on said sealing medium.

10. A booster compressor stage for refrigeration systems, said stagecomprising: a rotary vane-type compressor for gaseous refrigerant, saidcompressor having a suction line and a discharge line connected theretoand adapted to be connected in a refrigeration system, said compressorhaving a surrounding jacket for coolant circulation; a rotary driveshaft projecting from said compressor; a pair of packing members spacedapart on said shaft; a casing secured to said compressor surroundingsaid packing members and said drive shaft and having a surroundingjacket; a closed coolant circuit including a circulating pump and a heatexchanger connected to circulate a coolant through both of said jackets;a closed sealing medium circuit including a circulating pump and a heatexchanger connected to circulate a sealing medium through said casingbetween said packing members; and a pressure communicating connectionbetween said compressor discharge line and said sealing medium circuitfor maintaining a pressure on said sealing medium substantially equal tosaid compressor outlet pressure.

References Cited in the file of this patent UNITED STATES PATENTS NumberNumber Number Name Date Heim et al Apr. 6, 1897 Carrey Jan. 4, 1921Cuthbert Oct. 15, 1929 Steiner Apr. 25, 1933 Baumenn Nov. 6, 1934FOREIGN PATENTS Country Date Germany Sept. 26, 1940

